• Journal of Pharmaceutical Investigation
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• v.2 no.1
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• pp.5-13
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• 1972

There are some repels in which they studied on the change of acid-consuming capacity of aluminium hydroxide resulted from the passing of time. However, the relationship between grain sizes(particle sizes) and the acid-consuming capacity of dried aluminium hydroxide gel was not been studied. And studies on the grain sizes of aluminium hydroxide gel qualified by pharmacopoeia of Korea has not been reported. For the purpose of studying these two problems, the author prepared two-kinds of aluminium hydroxide gel as follows : $Na_2OAl_2O_3+CO_2------{\longrightarrow}Al(OH)_3{\cdots}{\cdots}{\cdots}$sample 1 $Al_2(SO_4)_318H_2O+6NaHCO_3{\longrightarrow}Al(OH)_3{\cdots}{\cdots}{\cdots}$sample 2 Both of sample 1 and 2 are found to be amorphous by X-ray diffraction methods, and their acid-consuming capacities were determined by the method of pharmacopeia of Korea. The grain size was measured by X-ray diffraction method, the particle sizes observed by electron microscopy, and the change of acid-consuming capacity with passing of time was determined by the method of pharmacopoeia of Korea. The results of these studies are summerized as follows: 1. The grain size was linearly enlarged as the time goes by. The aluminium hydroxide gel gradually crystallized in a certain period of time. 2. The acid-consuming capacity was in exponential function, decreased as the grain size of them enlarged. 3. One particle consists of tens of grains.4. Grinding the Sample obtained in any period of testing time in mortar did not change both their grain size and their acid-consuming capacity. 5. The grain size of dried aluminium hydroxide gel ought to be micronized less than $100{\AA}$ for maintaining the ability such as consumes 250m1 of 0. 1N-HC1 solution per Is of $Al(OH)_3$ described in pharmacopoeia of Korea.

• Journal of Powder Materials
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• v.20 no.5
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• pp.359-365
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• 2013

In this study, we fabricated $Nd_2Fe_{14}B$ hard magnetic powders with various sizes via spray drying combined with reduction-diffusion process. Spray drying is widely used to produce nearly spherical particles that are relatively homogeneous. Thus, the precursor particles were prepared by spray drying using the aqueous solution containing Nd salts, Fe salts and boric acid with the target stoichiometric composition of $Nd_2Fe_{14}B$. The mean particle sizes of the spray-dried powders are in the range from one to seven micrometer, which are adjusted by controlling the concentrations of precursor solutions. After debinding the as-prepared precursor particles, ball milling was also conducted to control the particle sizes of Nd-Fe-B oxide powders. The resulting particles with different sizes were subjected to subsequent treatments including hydrogen reduction, Ca reduction and washing for CaO removal. The size effect of Nd-Fe-B oxide particles on the formation of $Nd_2Fe_{14}B$ phase and magnetic properties was investigated.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.668-671
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• 2013

This paper describes activated carbon block filters prepared by extrusion for water purifier. The specific surface area of the activated carbon blocks affecting the properties of a polymer binder were investigated. Polyethylene (PE) particles were used as a binder polymer and the effect of particle sizes on changes in the specific surface area of activated carbon blocks in addition to the adsorption properties of chloride anion in the aqueous solution were investigated. The sizes and shapes of PE particles were measured using SEM. The specific surface area of activated carbon was $1186m^2/g$. The specific surface area of PE binder was $444m^2/g$ and $940m^2/g$ with the particle sizes of $200{\mu}m$ and $20{\mu}m$, respectively. In order to verify the performance of the filter, chlorine adsorption experiments were conducted.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3331-3337
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• 2012

Ru-modified Pt nanoparticles of various sizes on platelet carbon nanofiber toward methanol oxidation were investigated in terms of particle size effect. The sizes of Pt nanoparticles, prepared by polyol method, were in the range of 1.5-7.5 nm and Ru was spontaneously deposited by contacting Pt nanoparticles with the Ru precursor solutions of 2 and 5 mM. The Ru-modified Pt nanoparticles were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry. The methanol oxidation activities of Ru-modified Pt nanoparticles, measured using cyclic voltammetry and chronoamperometry, revealed that when the Pt particle size was less than 4.3 nm, the mass specific activity was fairly constant with an enhancement factor of more than 2 at 0.4 V. However, the surface area specific activity was maximized on Pt nanoparticles of 4.3 nm modified with 5 mM Ru precursor solution. The observations were discussed in terms of the enhancement of poison oxidation by Ru and the population variation of Pt atoms at vertices and edges of Pt nanoparticles due to selective deposition of Ru on the facets of (111) and (100).

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.3
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• pp.243-246
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• 1990

Sixteen mature sheep were fed chaffed orchardgrass hay once a day for 7 days. In 7th day, four sheep were slaughtered either prior to eating, 2, 8 or 16 hours after the commencement of eating to measure digesta pool size and particle size distribution in the reticulo-rumen. One sheep slaughtered at 8 hours after feeding had absesses at the cardia and in the lungs and could not ruminate normally. Time spent eating and rumination in the sheep on the day before slaughtering were 85 and 29 (pseudo-rumination 227) minutes a day, compared to those were 112 and 277 minutes in the other animals, respectively. Total actual chewing time in the sheep with absesses and the other animals were 98 and $373{\pm}132$ minutes, respectively. Dry matter(DM) intake in the sheep was $2.9g/kgBW^{0.75}$ which was only about 17% of that in the other animals. The pool sizes of reticulo-rumen DM and neutral detergent fiber (NDF) were somewhat smaller in the sheep than the others. The pool sizes of large particle (>1.18mm) DM and NDF in the animal were similar with those in the other animals. Mean DM retention time in the sheep was 207.4 hours which was about 4.2 times longer than that in the other animals.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.3
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• pp.225-229
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• 1990

Sixteen mature sheep were fed chaffed orchardgrass hay once a day. Jaw movement of the sheep was recorded for 24 hours before slaughter. Four sheep were slaughtered either prior to eating, 2, 8 or 16 hours after the commencement of eating to measure digesta pool size and particle size distribution in the reticulo-rumen. Eating time was restricted to 120 minutes. Rumination time and actual chewing time during rumination increased with time after the meal. Mean dry matter (DM) pool size before and 2 hours after the meal were 1.36 and 2.45 times of DM intake, respectively. The proportion of large particle (>1.18 mm; LP) in the DM ingested during the meal was caculated to be about 70%. The mean DM and LP pool sizes per DM intake and the mean proportion of LP in the DM pool decreased with time after the meal. There were close negative relationships between either DM or LP pool sizes per DM intake and the chewing activities either expressed as time spent rumination, actual chewing time during rumination or total actual chewing time(total of eating time and actual chewing time during rumination). The difference between DM intake and LP pool size were assumed to be LP degradation in the present experiment, and correlated positively with the chewing activities. A large proportion of the digesta load was comprised of small particles, in excess of the daily intake.

• Korean Journal of Materials Research
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• v.13 no.2
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• pp.106-110
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• 2003

Nano-sized powders of Indium Tin Oxide(ITO) were synthesized by a coprecipitation method. In order to investigate the gas sensing characteristics in the nanocrystalline ITO thick films with various particle sizes, ITO powders with the average particle diameter of 15, 30, and 70 nm respectively were synthesized. And the sensitivity of ITO thick films was measured upon exposure to a target gas($C_2$$H_{5}$ /OH) and some other Volatile Organic Compounds(VOCs), such as, toluene, methanol, benzene, chloroform. As a result, ITO thick films had high sensitivity for ethanol and higher sensitivity with smaller particle size.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2277-2288
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• 2021

To regulate the safety protocols in nuclear facilities, radioactive aerosols have been extensively researched to understand their health impacts. However, most measured particle-size distributions remain at low resolutions, with the particle sizes ranging from nanometer to micrometer. This study combines the high-resolution detection of 500 size classes, ranging from 6 nm to 10 ㎛, for aerodynamic diameter distributions, with a regional lung deposition calculation. We applied the new approach to characterize particle-size distributions of aerosols generated during the plasma arc cutting of simulated non-radioactive steel alloy wastes. The high-resolution measured data were used to calculate the deposition ratios of the aerosols in different lung regions. The deposition ratios in the alveolar sacs contained the dominant particle sizes ranging from 0.01 to 0.1 ㎛. We determined the distribution of various metals using different vapor pressures of the alloying components and analyzed the uncertainties of lung deposition calculations using the low-resolution aerodynamic diameter data simultaneously. In high-resolution data, the changes in aerosols that can penetrate the blood system were better captured, correcting their potential risks by a maximum of 42%. The combined calculations can aid the enhancement of high-resolution measuring equipment to effectively manage radiation safety in nuclear facilities.

• Food Science of Animal Resources
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• v.41 no.1
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• pp.110-121
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• 2021

Meat industries utilize plant material such as celery in cured meat products. Extraction of valuable bioactive compounds, nitrates and nitrites often involves processes that increase cost or lack sustainability. Thus, this study investigated the effect of ball-milled celery powders (CP) on the physicochemical, antioxidant, and antimicrobial properties along with curing efficiency in comminuted meat product. Pork sausages loaded with CPs with different average particle sizes: 265 ㎛ (T1), 68 ㎛ (T2) and 7 ㎛ (T3) were compared to those added without and with sodium nitrite (150 ppm). The a⁎ values were increased for sausages with larger particle size. The L⁎ values decreased for all CPs. Residual nitrite for all particle sizes increased in the earlier stages and decreased at the end of storage period. The curing efficiency also increased for larger size particles with an increase until day 9 followed by a gradual decrease. Superfine CP had a tendency to improve the antioxidant activities. The antimicrobial activity of CPs was not comparable with nitrite added sausages. The textural parameters remained unaffected by particle size. Thus, instead of extracts or juices, micronized CPs could be used to improve the antioxidant activities and curing efficiency of label friendly reformulated meat products.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.1013-1018
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• 2014

Magnetic Abrasive Polishing (MAP) process is a nontraditional method for polishing the surface of workpiece by using the flexibility of tool. At present, a mixture of polishing abrasives and ferrous particles is used as the tool in the MAP process. Previously, an experiment was conducted with different sizes of polishing abrasives with an aim to improve the polishing accuracy. However, the sizes of ferrous particles are also expected to have a dominant effect on the process, warranting a study on the effect of the size of ferrous iron particles. In this study, an experiment was conducted using three different sizes of ferrous particles. Iron powder of average diameters 8, 78 and $250{\mu}m$ was used as ferrous particles. The effect of each ferrous particle size was evaluated by comparing the improvements in surface roughness. The particle size of a ferrous iron was found to play a significant role in MAP and particles of $78{\mu}m$ facilitated the best improvement in surface roughness.